[Script Info] Title: [Events] Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text Dialogue: 0,0:00:01.57,0:00:03.59,Default,,0000,0000,0000,,Every summer when I was growing up, Dialogue: 0,0:00:03.61,0:00:06.99,Default,,0000,0000,0000,,I would fly from my home in Canada\Nto visit my grandparents, Dialogue: 0,0:00:07.02,0:00:08.82,Default,,0000,0000,0000,,who lived in Mumbai, India. Dialogue: 0,0:00:09.16,0:00:12.29,Default,,0000,0000,0000,,Now, Canadian summers\Nare pretty mild at best -- Dialogue: 0,0:00:12.32,0:00:16.02,Default,,0000,0000,0000,,about 22 degrees Celsius\Nor 72 degrees Fahrenheit Dialogue: 0,0:00:16.05,0:00:18.67,Default,,0000,0000,0000,,is a typical summer's day,\Nand not too hot. Dialogue: 0,0:00:19.28,0:00:22.32,Default,,0000,0000,0000,,Mumbai, on the other hand,\Nis a hot and humid place Dialogue: 0,0:00:22.34,0:00:25.56,Default,,0000,0000,0000,,well into the 30s Celsius\Nor 90s Fahrenheit. Dialogue: 0,0:00:26.36,0:00:27.95,Default,,0000,0000,0000,,As soon as I'd reach it, I'd ask, Dialogue: 0,0:00:27.97,0:00:32.38,Default,,0000,0000,0000,,"How could anyone live, work\Nor sleep in such weather?" Dialogue: 0,0:00:33.54,0:00:37.18,Default,,0000,0000,0000,,To make things worse, my grandparents\Ndidn't have an air conditioner. Dialogue: 0,0:00:37.77,0:00:40.59,Default,,0000,0000,0000,,And while I tried my very, very best, Dialogue: 0,0:00:40.62,0:00:43.37,Default,,0000,0000,0000,,I was never able\Nto persuade them to get one. Dialogue: 0,0:00:44.22,0:00:47.32,Default,,0000,0000,0000,,But this is changing, and fast. Dialogue: 0,0:00:47.91,0:00:52.26,Default,,0000,0000,0000,,Cooling systems today\Ncollectively account for 17 percent Dialogue: 0,0:00:52.28,0:00:54.65,Default,,0000,0000,0000,,of the electricity we use worldwide. Dialogue: 0,0:00:54.68,0:00:57.07,Default,,0000,0000,0000,,This includes everything\Nfrom the air conditioners Dialogue: 0,0:00:57.09,0:00:59.87,Default,,0000,0000,0000,,I so desperately wanted\Nduring my summer vacations, Dialogue: 0,0:00:59.90,0:01:03.50,Default,,0000,0000,0000,,to the refrigeration systems\Nthat keep our food safe and cold for us Dialogue: 0,0:01:03.53,0:01:04.76,Default,,0000,0000,0000,,in our supermarkets, Dialogue: 0,0:01:04.78,0:01:09.04,Default,,0000,0000,0000,,to the industrial scale systems\Nthat keep our data centers operational. Dialogue: 0,0:01:09.62,0:01:13.11,Default,,0000,0000,0000,,Collectively, these systems\Naccount for eight percent Dialogue: 0,0:01:13.13,0:01:15.38,Default,,0000,0000,0000,,of global greenhouse gas emissions. Dialogue: 0,0:01:15.82,0:01:17.43,Default,,0000,0000,0000,,But what keeps me up at night Dialogue: 0,0:01:17.46,0:01:22.38,Default,,0000,0000,0000,,is that our energy use for cooling\Nmight grow sixfold by the year 2050, Dialogue: 0,0:01:22.40,0:01:26.68,Default,,0000,0000,0000,,primarily driven by increasing usage\Nin Asian and African countries. Dialogue: 0,0:01:27.28,0:01:28.98,Default,,0000,0000,0000,,I've seen this firsthand. Dialogue: 0,0:01:29.01,0:01:32.16,Default,,0000,0000,0000,,Nearly every apartment\Nin and around my grandmother's place Dialogue: 0,0:01:32.19,0:01:34.21,Default,,0000,0000,0000,,now has an air conditioner. Dialogue: 0,0:01:34.24,0:01:37.28,Default,,0000,0000,0000,,And that is, emphatically, a good thing Dialogue: 0,0:01:37.31,0:01:40.01,Default,,0000,0000,0000,,for the health, well-being\Nand productivity Dialogue: 0,0:01:40.03,0:01:42.68,Default,,0000,0000,0000,,of people living in warmer climates. Dialogue: 0,0:01:43.83,0:01:47.77,Default,,0000,0000,0000,,However, one of the most\Nalarming things about climate change Dialogue: 0,0:01:47.80,0:01:50.39,Default,,0000,0000,0000,,is that the warmer our planet gets, Dialogue: 0,0:01:50.42,0:01:52.73,Default,,0000,0000,0000,,the more we're going to need\Ncooling systems -- Dialogue: 0,0:01:52.75,0:01:56.51,Default,,0000,0000,0000,,systems that are themselves large\Nemitters of greenhouse gas emissions. Dialogue: 0,0:01:57.24,0:02:00.57,Default,,0000,0000,0000,,This then has the potential\Nto cause a feedback loop, Dialogue: 0,0:02:00.59,0:02:02.05,Default,,0000,0000,0000,,where cooling systems alone Dialogue: 0,0:02:02.08,0:02:05.06,Default,,0000,0000,0000,,could become one of our biggest sources\Nof greenhouse gases Dialogue: 0,0:02:05.09,0:02:06.43,Default,,0000,0000,0000,,later this century. Dialogue: 0,0:02:06.74,0:02:07.91,Default,,0000,0000,0000,,In the worst case, Dialogue: 0,0:02:07.94,0:02:11.56,Default,,0000,0000,0000,,we might need more than 10 trillion\Nkilowatt-hours of electricity every year, Dialogue: 0,0:02:11.58,0:02:14.27,Default,,0000,0000,0000,,just for cooling, by the year 2100. Dialogue: 0,0:02:14.85,0:02:17.71,Default,,0000,0000,0000,,That's half our electricity supply today. Dialogue: 0,0:02:18.20,0:02:19.35,Default,,0000,0000,0000,,Just for cooling. Dialogue: 0,0:02:20.86,0:02:24.78,Default,,0000,0000,0000,,But this also point us\Nto an amazing opportunity. Dialogue: 0,0:02:25.44,0:02:30.01,Default,,0000,0000,0000,,A 10 or 20 percent improvement\Nin the efficiency of every cooling system Dialogue: 0,0:02:30.04,0:02:33.52,Default,,0000,0000,0000,,could actually have an enormous impact\Non our greenhouse gas emissions, Dialogue: 0,0:02:33.54,0:02:36.01,Default,,0000,0000,0000,,both today and later this century. Dialogue: 0,0:02:38.08,0:02:41.63,Default,,0000,0000,0000,,And it could help us avert\Nthat worst-case feedback loop. Dialogue: 0,0:02:42.93,0:02:46.61,Default,,0000,0000,0000,,I'm a scientist who thinks a lot\Nabout light and heat. Dialogue: 0,0:02:46.63,0:02:50.23,Default,,0000,0000,0000,,In particular, how new materials\Nallow us to alter the flow Dialogue: 0,0:02:50.25,0:02:52.27,Default,,0000,0000,0000,,of these basic elements of nature Dialogue: 0,0:02:52.29,0:02:54.93,Default,,0000,0000,0000,,in ways we might have\Nonce thought impossible. Dialogue: 0,0:02:55.32,0:02:57.73,Default,,0000,0000,0000,,So, while I always understood\Nthe value of cooling Dialogue: 0,0:02:57.75,0:02:59.70,Default,,0000,0000,0000,,during my summer vacations, Dialogue: 0,0:02:59.72,0:03:01.98,Default,,0000,0000,0000,,I actually wound up\Nworking on this problem Dialogue: 0,0:03:02.01,0:03:06.01,Default,,0000,0000,0000,,because of an intellectual puzzle\Nthat I came across about six years ago. Dialogue: 0,0:03:07.15,0:03:12.77,Default,,0000,0000,0000,,How were ancient peoples\Nable to make ice in desert climates? Dialogue: 0,0:03:13.89,0:03:16.83,Default,,0000,0000,0000,,This is a picture of an ice house, Dialogue: 0,0:03:16.85,0:03:20.48,Default,,0000,0000,0000,,also called a Yakhchal,\Nlocated in the southwest of Iran. Dialogue: 0,0:03:21.01,0:03:24.76,Default,,0000,0000,0000,,There are ruins of dozens\Nof such structures throughout Iran, Dialogue: 0,0:03:24.78,0:03:28.47,Default,,0000,0000,0000,,with evidence of similar such buildings\Nthroughout the rest of the Middle East Dialogue: 0,0:03:28.50,0:03:29.71,Default,,0000,0000,0000,,and all the way to China. Dialogue: 0,0:03:30.23,0:03:33.42,Default,,0000,0000,0000,,The people who operated\Nthis ice house many centuries ago, Dialogue: 0,0:03:33.44,0:03:35.93,Default,,0000,0000,0000,,would pour water\Nin the pool you see on the left Dialogue: 0,0:03:35.95,0:03:39.02,Default,,0000,0000,0000,,in the early evening hours,\Nas the sun set. Dialogue: 0,0:03:39.05,0:03:40.86,Default,,0000,0000,0000,,And then something amazing happened. Dialogue: 0,0:03:41.44,0:03:44.20,Default,,0000,0000,0000,,Even though the air temperature\Nmight be above freezing, Dialogue: 0,0:03:44.23,0:03:47.93,Default,,0000,0000,0000,,say five degrees Celsius\Nor 41 degrees Fahrenheit, Dialogue: 0,0:03:47.95,0:03:49.48,Default,,0000,0000,0000,,the water would freeze. Dialogue: 0,0:03:50.72,0:03:54.86,Default,,0000,0000,0000,,The ice generated would then be collected\Nin the early morning hours Dialogue: 0,0:03:54.88,0:03:57.52,Default,,0000,0000,0000,,and stored for use in the building\Nyou see on the right, Dialogue: 0,0:03:57.54,0:03:59.48,Default,,0000,0000,0000,,all the way through the summer months. Dialogue: 0,0:04:00.13,0:04:02.85,Default,,0000,0000,0000,,You've actually likely seen\Nsomething very similar at play Dialogue: 0,0:04:02.88,0:04:06.33,Default,,0000,0000,0000,,if you've ever noticed frost form\Non the ground on a clear night, Dialogue: 0,0:04:06.35,0:04:09.10,Default,,0000,0000,0000,,even when the air temperature\Nis well above freezing. Dialogue: 0,0:04:09.12,0:04:10.28,Default,,0000,0000,0000,,But wait. Dialogue: 0,0:04:10.30,0:04:14.04,Default,,0000,0000,0000,,How did the water freeze\Nif the air temperature is above freezing? Dialogue: 0,0:04:14.49,0:04:16.41,Default,,0000,0000,0000,,Evaporation could have played an effect, Dialogue: 0,0:04:16.44,0:04:19.75,Default,,0000,0000,0000,,but that's not enough to actually\Ncause the water to become ice. Dialogue: 0,0:04:20.06,0:04:22.15,Default,,0000,0000,0000,,Something else must have cooled it down. Dialogue: 0,0:04:22.76,0:04:25.31,Default,,0000,0000,0000,,Think about a pie\Ncooling on a window sill. Dialogue: 0,0:04:25.62,0:04:29.23,Default,,0000,0000,0000,,For it to be able to cool down,\Nits heat needs to flow somewhere cooler. Dialogue: 0,0:04:29.25,0:04:31.16,Default,,0000,0000,0000,,Namely, the air that surrounds it. Dialogue: 0,0:04:32.18,0:04:34.49,Default,,0000,0000,0000,,As implausible as it may sound, Dialogue: 0,0:04:34.51,0:04:39.89,Default,,0000,0000,0000,,for that pool of water, its heat\Nis actually flowing to the cold of space. Dialogue: 0,0:04:42.08,0:04:43.81,Default,,0000,0000,0000,,How is this possible? Dialogue: 0,0:04:44.43,0:04:48.01,Default,,0000,0000,0000,,Well, that pool of water,\Nlike most natural materials, Dialogue: 0,0:04:48.03,0:04:50.18,Default,,0000,0000,0000,,sends out its heat as light. Dialogue: 0,0:04:50.51,0:04:53.32,Default,,0000,0000,0000,,This is a concept\Nknown as thermal radiation. Dialogue: 0,0:04:53.79,0:04:58.26,Default,,0000,0000,0000,,In fact, we're all sending out our heat\Nas infrared light right now, Dialogue: 0,0:04:58.28,0:05:00.21,Default,,0000,0000,0000,,to each other and our surroundings. Dialogue: 0,0:05:00.61,0:05:03.08,Default,,0000,0000,0000,,We can actually visualize this\Nwith thermal cameras Dialogue: 0,0:05:03.10,0:05:06.35,Default,,0000,0000,0000,,and the images they produce,\Nlike the ones I'm showing you right now. Dialogue: 0,0:05:06.74,0:05:09.01,Default,,0000,0000,0000,,So that pool of water\Nis sending out its heat Dialogue: 0,0:05:09.03,0:05:10.71,Default,,0000,0000,0000,,upward towards the atmosphere. Dialogue: 0,0:05:11.38,0:05:13.47,Default,,0000,0000,0000,,The atmosphere and the molecules in it Dialogue: 0,0:05:13.50,0:05:16.05,Default,,0000,0000,0000,,absorb some of that heat and send it back. Dialogue: 0,0:05:16.08,0:05:19.90,Default,,0000,0000,0000,,That's actually the greenhouse effect\Nthat's responsible for climate change. Dialogue: 0,0:05:20.44,0:05:22.96,Default,,0000,0000,0000,,But here's the critical thing\Nto understand. Dialogue: 0,0:05:22.98,0:05:26.18,Default,,0000,0000,0000,,Our atmosphere doesn't absorb\Nall of that heat. Dialogue: 0,0:05:26.58,0:05:29.51,Default,,0000,0000,0000,,If it did, we'd be\Non a much warmer planet. Dialogue: 0,0:05:29.98,0:05:31.49,Default,,0000,0000,0000,,At certain wavelengths, Dialogue: 0,0:05:31.51,0:05:34.97,Default,,0000,0000,0000,,in particular between\Neight and 13 microns, Dialogue: 0,0:05:34.99,0:05:38.75,Default,,0000,0000,0000,,our atmosphere has what's known\Nas a transmission window. Dialogue: 0,0:05:39.40,0:05:44.92,Default,,0000,0000,0000,,This window allows some of the heat\Nthat goes up as infrared light Dialogue: 0,0:05:44.94,0:05:48.28,Default,,0000,0000,0000,,to effectively escape,\Ncarrying away that pool's heat. Dialogue: 0,0:05:48.90,0:05:52.66,Default,,0000,0000,0000,,And it can escape to a place\Nthat is much, much colder. Dialogue: 0,0:05:53.63,0:05:55.60,Default,,0000,0000,0000,,The cold of this upper atmosphere Dialogue: 0,0:05:55.62,0:05:57.30,Default,,0000,0000,0000,,and all the way out to outer space, Dialogue: 0,0:05:57.32,0:06:01.13,Default,,0000,0000,0000,,which can be as cold\Nas minus 270 degrees Celsius, Dialogue: 0,0:06:01.16,0:06:03.88,Default,,0000,0000,0000,,or minus 454 degrees Fahrenheit. Dialogue: 0,0:06:05.24,0:06:08.61,Default,,0000,0000,0000,,So that pool of water is able\Nto send out more heat to the sky Dialogue: 0,0:06:08.63,0:06:10.40,Default,,0000,0000,0000,,than the sky sends back to it. Dialogue: 0,0:06:10.42,0:06:11.58,Default,,0000,0000,0000,,And because of that, Dialogue: 0,0:06:11.60,0:06:14.62,Default,,0000,0000,0000,,the pool will cool down\Nbelow its surroundings' temperature. Dialogue: 0,0:06:16.04,0:06:19.55,Default,,0000,0000,0000,,This is an effect\Nknown as night-sky cooling Dialogue: 0,0:06:19.58,0:06:20.98,Default,,0000,0000,0000,,or radiative cooling. Dialogue: 0,0:06:21.37,0:06:24.82,Default,,0000,0000,0000,,And it's always been understood\Nby climate scientists and meteorologists Dialogue: 0,0:06:24.85,0:06:27.45,Default,,0000,0000,0000,,as a very important natural phenomenon. Dialogue: 0,0:06:28.88,0:06:30.37,Default,,0000,0000,0000,,When I came across all of this, Dialogue: 0,0:06:30.40,0:06:33.04,Default,,0000,0000,0000,,it was towards the end\Nof my PhD at Stanford. Dialogue: 0,0:06:33.06,0:06:37.49,Default,,0000,0000,0000,,And I was amazed by its apparent\Nsimplicity as a cooling method, Dialogue: 0,0:06:37.51,0:06:38.78,Default,,0000,0000,0000,,yet really puzzled. Dialogue: 0,0:06:39.28,0:06:41.48,Default,,0000,0000,0000,,Why aren't we making use of this? Dialogue: 0,0:06:42.74,0:06:45.62,Default,,0000,0000,0000,,Now, scientists and engineers\Nhad investigated this idea Dialogue: 0,0:06:45.65,0:06:46.89,Default,,0000,0000,0000,,in previous decades. Dialogue: 0,0:06:46.91,0:06:50.20,Default,,0000,0000,0000,,But there turned out to be\Nat least one big problem. Dialogue: 0,0:06:50.88,0:06:53.75,Default,,0000,0000,0000,,It was called night-sky\Ncooling for a reason. Dialogue: 0,0:06:54.11,0:06:55.28,Default,,0000,0000,0000,,Why? Dialogue: 0,0:06:55.31,0:06:57.68,Default,,0000,0000,0000,,Well, it's a little thing called the sun. Dialogue: 0,0:06:58.16,0:07:00.62,Default,,0000,0000,0000,,So, for the surface\Nthat's doing the cooling, Dialogue: 0,0:07:00.64,0:07:02.82,Default,,0000,0000,0000,,it needs to be able to face the sky. Dialogue: 0,0:07:02.84,0:07:04.47,Default,,0000,0000,0000,,And during the middle of the day, Dialogue: 0,0:07:04.49,0:07:07.64,Default,,0000,0000,0000,,when we might want\Nsomething cold the most, Dialogue: 0,0:07:07.66,0:07:10.56,Default,,0000,0000,0000,,unfortunately, that means\Nyou're going to look up to the sun. Dialogue: 0,0:07:10.58,0:07:12.44,Default,,0000,0000,0000,,And the sun heats most materials up Dialogue: 0,0:07:12.46,0:07:15.22,Default,,0000,0000,0000,,enough to completely counteract\Nthis cooling effect. Dialogue: 0,0:07:16.41,0:07:18.42,Default,,0000,0000,0000,,My colleagues and I\Nspend a lot of our time Dialogue: 0,0:07:18.44,0:07:20.55,Default,,0000,0000,0000,,thinking about how\Nwe can structure materials Dialogue: 0,0:07:20.58,0:07:21.99,Default,,0000,0000,0000,,at very small length scales Dialogue: 0,0:07:22.01,0:07:25.34,Default,,0000,0000,0000,,such that they can do\Nnew and useful things with light -- Dialogue: 0,0:07:25.36,0:07:28.35,Default,,0000,0000,0000,,length scales smaller\Nthan the wavelength of light itself. Dialogue: 0,0:07:28.38,0:07:29.96,Default,,0000,0000,0000,,Using insights from this field, Dialogue: 0,0:07:29.98,0:07:33.11,Default,,0000,0000,0000,,known as nanophotonics\Nor metamaterials research, Dialogue: 0,0:07:33.13,0:07:36.63,Default,,0000,0000,0000,,we realized that there might be a way\Nto make this possible during the day Dialogue: 0,0:07:36.66,0:07:37.83,Default,,0000,0000,0000,,for the first time. Dialogue: 0,0:07:37.85,0:07:40.91,Default,,0000,0000,0000,,To do this, I designed\Na multilayer optical material Dialogue: 0,0:07:40.93,0:07:42.79,Default,,0000,0000,0000,,shown here in a microscope image. Dialogue: 0,0:07:42.82,0:07:46.20,Default,,0000,0000,0000,,It's more than 40 times thinner\Nthan a typical human hair. Dialogue: 0,0:07:46.22,0:07:48.74,Default,,0000,0000,0000,,And it's able to do\Ntwo things simultaneously. Dialogue: 0,0:07:49.17,0:07:50.99,Default,,0000,0000,0000,,First, it sends its heat out Dialogue: 0,0:07:51.02,0:07:54.82,Default,,0000,0000,0000,,precisely where our atmosphere\Nlets that heat out the best. Dialogue: 0,0:07:54.84,0:07:56.98,Default,,0000,0000,0000,,We targeted the window to space. Dialogue: 0,0:07:57.52,0:08:00.95,Default,,0000,0000,0000,,The second thing it does\Nis it avoids getting heated up by the sun. Dialogue: 0,0:08:00.97,0:08:03.37,Default,,0000,0000,0000,,It's a very good mirror to sunlight. Dialogue: 0,0:08:04.32,0:08:07.03,Default,,0000,0000,0000,,The first time I tested this\Nwas on a rooftop in Stanford Dialogue: 0,0:08:07.05,0:08:08.82,Default,,0000,0000,0000,,that I'm showing you right here. Dialogue: 0,0:08:09.34,0:08:11.72,Default,,0000,0000,0000,,I left the device out for a little while, Dialogue: 0,0:08:11.74,0:08:14.82,Default,,0000,0000,0000,,and I walked up to it after a few minutes, Dialogue: 0,0:08:14.84,0:08:17.63,Default,,0000,0000,0000,,and within seconds, I knew it was working. Dialogue: 0,0:08:17.66,0:08:18.82,Default,,0000,0000,0000,,How? Dialogue: 0,0:08:18.84,0:08:20.47,Default,,0000,0000,0000,,I touched it, and it felt cold. Dialogue: 0,0:08:21.40,0:08:26.05,Default,,0000,0000,0000,,(Applause) Dialogue: 0,0:08:26.86,0:08:30.85,Default,,0000,0000,0000,,Just to emphasize how weird\Nand counterintuitive this is: Dialogue: 0,0:08:30.87,0:08:32.60,Default,,0000,0000,0000,,this material and others like it Dialogue: 0,0:08:32.62,0:08:35.53,Default,,0000,0000,0000,,will get colder when we take them\Nout of the shade, Dialogue: 0,0:08:35.55,0:08:37.91,Default,,0000,0000,0000,,even though the sun is shining on it. Dialogue: 0,0:08:37.94,0:08:40.62,Default,,0000,0000,0000,,I'm showing you data here\Nfrom our very first experiment, Dialogue: 0,0:08:40.64,0:08:43.38,Default,,0000,0000,0000,,where that material stayed\Nmore than five degrees Celsius, Dialogue: 0,0:08:43.41,0:08:46.68,Default,,0000,0000,0000,,or nine degrees Fahrenheit, colder\Nthan the air temperature, Dialogue: 0,0:08:46.71,0:08:49.52,Default,,0000,0000,0000,,even though the sun\Nwas shining directly on it. Dialogue: 0,0:08:50.86,0:08:53.99,Default,,0000,0000,0000,,The manufacturing method we used\Nto actually make this material Dialogue: 0,0:08:54.01,0:08:56.55,Default,,0000,0000,0000,,already exists at large volume scales. Dialogue: 0,0:08:56.90,0:08:58.06,Default,,0000,0000,0000,,So I was really excited, Dialogue: 0,0:08:58.08,0:09:01.12,Default,,0000,0000,0000,,because not only\Ndo we make something cool, Dialogue: 0,0:09:01.15,0:09:06.20,Default,,0000,0000,0000,,but we might actually have the opportunity\Nto do something real and make it useful. Dialogue: 0,0:09:07.20,0:09:09.12,Default,,0000,0000,0000,,That brings me to the next big question. Dialogue: 0,0:09:09.14,0:09:11.73,Default,,0000,0000,0000,,How do you actually\Nsave energy with this idea? Dialogue: 0,0:09:11.75,0:09:15.41,Default,,0000,0000,0000,,Well, we believe the most direct way\Nto save energy with this technology Dialogue: 0,0:09:15.43,0:09:17.09,Default,,0000,0000,0000,,is as an efficiency boost Dialogue: 0,0:09:17.12,0:09:20.18,Default,,0000,0000,0000,,for today's air-conditioning\Nand refrigeration systems. Dialogue: 0,0:09:20.56,0:09:22.72,Default,,0000,0000,0000,,To do this, we've built\Nfluid cooling panels, Dialogue: 0,0:09:22.74,0:09:24.32,Default,,0000,0000,0000,,like the ones shown right here. Dialogue: 0,0:09:24.34,0:09:27.01,Default,,0000,0000,0000,,These panels have a similar shape\Nto solar water heaters, Dialogue: 0,0:09:27.03,0:09:29.95,Default,,0000,0000,0000,,except they do the opposite --\Nthey cool the water, passively, Dialogue: 0,0:09:29.97,0:09:32.04,Default,,0000,0000,0000,,using our specialized material. Dialogue: 0,0:09:32.82,0:09:35.28,Default,,0000,0000,0000,,These panels can then\Nbe integrated with a component Dialogue: 0,0:09:35.30,0:09:37.87,Default,,0000,0000,0000,,almost every cooling system has,\Ncalled a condenser, Dialogue: 0,0:09:37.89,0:09:41.02,Default,,0000,0000,0000,,to improve the system's\Nunderlying efficiency. Dialogue: 0,0:09:41.37,0:09:43.26,Default,,0000,0000,0000,,Our start-up, SkyCool Systems, Dialogue: 0,0:09:43.29,0:09:47.16,Default,,0000,0000,0000,,has recently completed a field trial\Nin Davis, California, shown right here. Dialogue: 0,0:09:47.65,0:09:48.83,Default,,0000,0000,0000,,In that demonstration, Dialogue: 0,0:09:48.86,0:09:51.90,Default,,0000,0000,0000,,we showed that we could actually\Nimprove the efficiency Dialogue: 0,0:09:51.93,0:09:54.85,Default,,0000,0000,0000,,of that cooling system\Nas much as 12 percent in the field. Dialogue: 0,0:09:55.47,0:09:56.73,Default,,0000,0000,0000,,Over the next year or two, Dialogue: 0,0:09:56.75,0:10:00.66,Default,,0000,0000,0000,,I'm super excited to see this go\Nto its first commercial-scale pilots Dialogue: 0,0:10:00.68,0:10:03.82,Default,,0000,0000,0000,,in both the air conditioning\Nand refrigeration space. Dialogue: 0,0:10:04.26,0:10:07.85,Default,,0000,0000,0000,,In the future, we might be able\Nto integrate these kinds of panels Dialogue: 0,0:10:07.87,0:10:11.18,Default,,0000,0000,0000,,with higher efficiency\Nbuilding cooling systems Dialogue: 0,0:10:11.20,0:10:14.01,Default,,0000,0000,0000,,to reduce their energy\Nusage by two-thirds. Dialogue: 0,0:10:14.03,0:10:17.69,Default,,0000,0000,0000,,And eventually, we might actually\Nbe able to build a cooling system Dialogue: 0,0:10:17.71,0:10:20.28,Default,,0000,0000,0000,,that requires no electricity input at all. Dialogue: 0,0:10:20.97,0:10:22.48,Default,,0000,0000,0000,,As a first step towards that, Dialogue: 0,0:10:22.51,0:10:24.36,Default,,0000,0000,0000,,my colleagues at Stanford and I Dialogue: 0,0:10:24.39,0:10:26.41,Default,,0000,0000,0000,,have shown that you could\Nactually maintain Dialogue: 0,0:10:26.44,0:10:31.01,Default,,0000,0000,0000,,something more than 42 degrees Celsius\Nbelow the air temperature Dialogue: 0,0:10:31.03,0:10:32.42,Default,,0000,0000,0000,,with better engineering. Dialogue: 0,0:10:33.16,0:10:34.32,Default,,0000,0000,0000,,Thank you. Dialogue: 0,0:10:34.34,0:10:38.39,Default,,0000,0000,0000,,(Applause) Dialogue: 0,0:10:39.20,0:10:40.35,Default,,0000,0000,0000,,So just imagine that -- Dialogue: 0,0:10:40.37,0:10:43.77,Default,,0000,0000,0000,,something that is below freezing\Non a hot summer's day. Dialogue: 0,0:10:45.93,0:10:50.41,Default,,0000,0000,0000,,So, while I'm very excited\Nabout all we can do for cooling, Dialogue: 0,0:10:50.43,0:10:53.69,Default,,0000,0000,0000,,and I think there's a lot yet to be done, Dialogue: 0,0:10:53.71,0:10:57.18,Default,,0000,0000,0000,,as a scientist, I'm also drawn\Nto a more profound opportunity Dialogue: 0,0:10:57.20,0:10:59.22,Default,,0000,0000,0000,,that I believe this work highlights. Dialogue: 0,0:10:59.76,0:11:02.90,Default,,0000,0000,0000,,We can use the cold darkness of space Dialogue: 0,0:11:02.92,0:11:04.57,Default,,0000,0000,0000,,to improve the efficiency Dialogue: 0,0:11:04.59,0:11:07.85,Default,,0000,0000,0000,,of every energy-related\Nprocess here on earth. Dialogue: 0,0:11:09.20,0:11:12.52,Default,,0000,0000,0000,,One such process\NI'd like to highlight are solar cells. Dialogue: 0,0:11:12.93,0:11:14.38,Default,,0000,0000,0000,,They heat up under the sun Dialogue: 0,0:11:14.40,0:11:16.89,Default,,0000,0000,0000,,and become less efficient\Nthe hotter they are. Dialogue: 0,0:11:17.28,0:11:21.15,Default,,0000,0000,0000,,In 2015, we showed that\Nwith deliberate kinds of microstructures Dialogue: 0,0:11:21.18,0:11:22.72,Default,,0000,0000,0000,,on top of a solar cell, Dialogue: 0,0:11:22.75,0:11:25.59,Default,,0000,0000,0000,,we could take better advantage\Nof this cooling effect Dialogue: 0,0:11:25.62,0:11:29.32,Default,,0000,0000,0000,,to maintain a solar cell passively\Nat a lower temperature. Dialogue: 0,0:11:29.71,0:11:32.03,Default,,0000,0000,0000,,This allows the cell\Nto operate more efficiently. Dialogue: 0,0:11:32.63,0:11:35.60,Default,,0000,0000,0000,,We're probing these kinds\Nof opportunities further. Dialogue: 0,0:11:35.62,0:11:38.86,Default,,0000,0000,0000,,We're asking whether\Nwe can use the cold of space Dialogue: 0,0:11:38.89,0:11:40.97,Default,,0000,0000,0000,,to help us with water conservation. Dialogue: 0,0:11:41.32,0:11:43.66,Default,,0000,0000,0000,,Or perhaps with off-grid scenarios. Dialogue: 0,0:11:43.69,0:11:47.86,Default,,0000,0000,0000,,Perhaps we could even directly\Ngenerate power with this cold. Dialogue: 0,0:11:48.52,0:11:51.48,Default,,0000,0000,0000,,There's a large temperature difference\Nbetween us here on earth Dialogue: 0,0:11:51.50,0:11:53.19,Default,,0000,0000,0000,,and the cold of space. Dialogue: 0,0:11:53.21,0:11:55.34,Default,,0000,0000,0000,,That difference, at least conceptually, Dialogue: 0,0:11:55.36,0:11:57.96,Default,,0000,0000,0000,,could be used to drive\Nsomething called a heat engine Dialogue: 0,0:11:57.98,0:11:59.17,Default,,0000,0000,0000,,to generate electricity. Dialogue: 0,0:11:59.97,0:12:03.57,Default,,0000,0000,0000,,Could we then make a nighttime\Npower-generation device Dialogue: 0,0:12:03.59,0:12:05.99,Default,,0000,0000,0000,,that generates useful\Namounts of electricity Dialogue: 0,0:12:06.02,0:12:07.92,Default,,0000,0000,0000,,when solar cells don't work? Dialogue: 0,0:12:07.94,0:12:10.48,Default,,0000,0000,0000,,Could we generate light from darkness? Dialogue: 0,0:12:11.87,0:12:16.26,Default,,0000,0000,0000,,Central to this ability\Nis being able to manage Dialogue: 0,0:12:16.28,0:12:19.40,Default,,0000,0000,0000,,the thermal radiation\Nthat's all around us. Dialogue: 0,0:12:19.42,0:12:22.22,Default,,0000,0000,0000,,We're constantly bathed in infrared light; Dialogue: 0,0:12:22.67,0:12:25.12,Default,,0000,0000,0000,,if we could bend it to our will, Dialogue: 0,0:12:25.14,0:12:27.87,Default,,0000,0000,0000,,we could profoundly change\Nthe flows of heat and energy Dialogue: 0,0:12:27.90,0:12:30.63,Default,,0000,0000,0000,,that permeate around us every single day. Dialogue: 0,0:12:31.19,0:12:34.53,Default,,0000,0000,0000,,This ability, coupled\Nwith the cold darkness of space, Dialogue: 0,0:12:34.56,0:12:37.86,Default,,0000,0000,0000,,points us to a future\Nwhere we, as a civilization, Dialogue: 0,0:12:37.89,0:12:43.13,Default,,0000,0000,0000,,might be able to more intelligently manage\Nour thermal energy footprint Dialogue: 0,0:12:43.15,0:12:44.95,Default,,0000,0000,0000,,at the very largest scales. Dialogue: 0,0:12:45.90,0:12:48.12,Default,,0000,0000,0000,,As we confront climate change, Dialogue: 0,0:12:48.14,0:12:50.74,Default,,0000,0000,0000,,I believe having\Nthis ability in our toolkit Dialogue: 0,0:12:50.77,0:12:52.57,Default,,0000,0000,0000,,will prove to be essential. Dialogue: 0,0:12:53.43,0:12:56.63,Default,,0000,0000,0000,,So, the next time\Nyou're walking around outside, Dialogue: 0,0:12:56.65,0:13:02.99,Default,,0000,0000,0000,,yes, do marvel at how the sun\Nis essential to life on earth itself, Dialogue: 0,0:13:03.02,0:13:07.69,Default,,0000,0000,0000,,but don't forget that the rest of the sky\Nhas something to offer us as well. Dialogue: 0,0:13:08.53,0:13:09.68,Default,,0000,0000,0000,,Thank you. Dialogue: 0,0:13:09.71,0:13:13.82,Default,,0000,0000,0000,,(Applause)